This invention relates to an improvement in the trailer section of a truck/trailer or cab/trailer assembly.
Previously, support wheels and legs have been provided for cab drawn trailers ahead of the center of gravity of the stopped or static said trailer. Further, some sets of hydraulically extendable vertical legs have been provided at more than one position along the length of the trailer for various purposes. However, there is one basic arrangement common to essentially all trailers lying in the fact that, once the prime mover, trailer or cab has been disengaged from the trailer, the trailer must stand, level and secure, at its release point or position for loading or unloading. An example of a vehicle which would be integral with respect to the cab and the trailer (the two not detachable) yet use one or more pairs of stabilizing or position holding hydraulic jacks would be a crane, where a multiplicity of opposed hydraulic jacks are provided in order to be able to lift the crane assembly off the wheels and onto the hydraulic jack pattern.
In the subject development, a substitution of three substantially fully retractable hydraulic cylinders is provided along the length of the trailer forward of the front center of gravity thereof, whereby to be able to effect substantially completely protected travel of the cylinders, with their receiving, supporting and connecting means, yet thereafter be able to supply fully effective and immediately actuatable support means when the vehicle is stopped and it is desired to disengage the cab assembly from the trailer assembly.
Thus, the subject apparatus has, as a primary use, to lift and support the front end of the static trailer and allow the tractor to pull away from it leaving the trailer to stand on its own.
In a specific example, my invention is comprised of a twelve (12) volt hydraulic pump, such run by connecting it to the already available electric plug of the truck that is normally connected to the tractor. The latter line will be the source of electricity needed for the pump. There are provided five (5) 24 inch long by 1/2 inch diameter hoses and one 15 inch by 1/2 inch diameter hose, all of them leading to and from the hydraulic cylinders and carrying hydraulic fluid to the two sometimes vertical hydraulic cylinders and the translating cylinders. Such cylinders are the dollies that will raise or lower as desired and hold the trailor in place. These cylinders typically will support 35,000 pounds per cylinder. These remarks are illustrative only, not limiting.
When these cylinders are attached to a large semi-trailer, they will swing up flush against the bottom of the trailer and be held there by a third hydraulic cylinder, when the tractor is engaged with the trailer, thus being effectively out of the way when not in use. It follows that they are not likely to drag on a bump or hill and become bent or dented. The latter often happens with the dollies being used now. Still further, by being drawn up next to the bottom of the trailer, these new dollies will have protection from snow and ice; so as to save the truck driver the problem of freeing them from such snow and ice before he can support the trailer in order to remove the tractor from it. The 12 volt hydraulic pump is turned on or off with a flick of a switch, thus saving the driver a job of one hour or more of hand cranking to get the sleeve extentions down to hold the trailer.